Liquid crystal display (LCD) that possesses advantages such as small size, low power consumption and no radiation has been rapidly developed in recent years, and has dominated the current market of flat-panel displays (FPDs). At present, LCD is widely applied in various products with large, middle and small sizes, which nearly covers the main electronic products in today's information society, for example, LCD TV, high definition digital TV, computer (including desktop computer and notebook computer), mobile phone, vehicle-mounted display, projected display, video camera, digital camera, electronic watch, calculator, electronic instrument, gauge, public display, virtual display and the like.